I made this little scooter for my son Max in about an hour from a little kid's bike (Max's first bike in fact) with 12" wheels. He became very good at scootering very quickly with it, and it's a LOT safer than one of those Razor scooters.
I bought a couple pretty nice older 10 speeds and a nice chrome moly Redline BMX bike at a yard sale, all for $5! I turned both 10 speeds into matching kickbicks, modelled after the ones at www.kickbike.com. I keep one at work and one at home. They're GREAT for riding with young children on bikes that don't go so fast. Everybody gets excercise that way. At work it's perfect for errands. You have to be ok with people gawking at you when you ride a kickbike. EVERYONE looks if not outright stares at you.